Electrical oxygen vaporizer and protecting cover



Nov. 30,1948. J. A. MATHIS ET AL 2,454,934

I ELECTRICAL OXYGEN VAPORIZER AND PROTECTING COVER Filed Jan. 24, 1947 j 5 Sheets-Sheet 1 Fl. I.

U INV NTORS JOHN A. MA THIS ROLAND W. MILAN Nov. 30, 1948. 5 .I. A. MATHIS ETAL 2,454,934

ELECTRICAL OXYGEN VAPORIZER AND PROTECTING COVER Filed Jan. 24,,- 1947 v 5 Sheets-Sheet 2 INVENTORS JOHN A MA THIS ROLAND W MILAN Nov.30, 1948. J. A. M ATHI S ETAL ,4

ELECTRICAL OXYGEN VAPORIZER m PROTECTING COVER Filed Jan. 24, 1947 f '5 Shets-Sheet s L IOUID OXYGEN FI LLING VALVE GAS RELEASE VALV E PRESSURE- nzsvousw: s w 'r c 1 MAIN GAS RELAY DISCHARGE VALVE INVENTORS JOHN A. MA THIS ROLAND W MILAN Nov. 30, 1948. .1. A. MATHIS ETALY ELECTRICAL OXYGEN VAPORIZER AND PROTECTING GOVER f 5 Sheets-Sheet 4 Filed Jan.- 24, 1947 4 JOHNA. MATH/5 ROLAND m M/LA/V Nov. 30, 1948. J. A. MATHIS ET AL 2,454,934

ELECTRICAL OXYGENqiVAPdRIZER AND PROTECTING (DOVER I Filed Jan. 24, 1.947 5 Sheets-Sheet 5 FIG. 6.

k\- INVENTORS JOHNAMATHIS ROLAND! MIL-J4!!! Patented Nov. 30, 1948 ELECTRICAL OXYGEN VAPORIZER AND PROTECTING COVER John A. Mathis and Roland W. Milan, Pinckneyville, Ill.

Application January 24, 1947, Serial No. 724,202

. 9 Claims. 1

This invention relates to apparatus for converting liquified gases and particularly oxygen into gaseous form at a controlled rate, and is an improvement upon the constructions shown in our two previously granted Patents Nos. 2,158,458 issued May 16, 1939, and 2,401,651 issued June 4, 1946.

One object of the present invention is to provide an improved construction for a container of the spaced wall, evacuated type for liquifled gas that is much safer to use than the prior known containers and which will not inflict injury upon personnel or cause property damage in the event of a rupture of the inner Wall of the container.

Another Object is to provide an improved arrangement for automatically increasing the rate at which the liquid oxygen is normally converted to its gaseous form to satisfy temporary peak demands for the oxygen.

Another object is to provide for selectively delivering the gas at either its normal rate as determined by the heating capacity of the electric heater unit or at a much higher rate.

Yet another object is an improved arrangement of an electrical heater element and thermostat in a double walled vessel of the Dewar flask type used for dispensing a liquefied gas in vapor form.

A more specific object of the invention is to provide an improved Dewar flask type oxygen converter that includes a valve controlled liquid inlet, a valve controlled gas outlet and a valve controlled connection between the inlet and outlet for admitting liquid oxygen directly into the gas outlet so that the volume of gas normally generated by heating the liquid within the flask may be augmented when necessary by direct evaporation of the liquid from the inlet.

These and other objects and advantages derived from the invention will become more apparent from the following detailed description when considered with the accompanying drawings in which:

Fig. 1 is a front elevation of the apparatus;

Fig. 2 is a central, vertical section of the apparatus;

Fig. 3 is a diagram of the gas-valve electrical system:

Fig. 4 is a horizontal section taken on line 4-4 of Fig. 2;

Fig. 5 is a horizontal section taken on line 5-5 of Fig. 2;

Fig. 6 is a detail vertical section taken on line B--B of Fig. 2, parts being shown in elevation;

Fig. '7 is a fractional horizontal section taken on line 1-l of Fig. 2; r

Fig. 8 is a plan view of the liquid level indicator:

Fig. 9 is a vertical section taken on line 9-9 of Fig. 8, a part of the dial being broken away; and

Fig. 10 is a detail vertical section taken on line Ill-Illof Fig. 2.

Referring now to the drawings, the improved oxygen converter is a generally spherical flask comprising inner and outer concentric hollow spheres I and 2, the space between the two spheres being evacuated in the usual manner to prevent the transfer of heat between the surrounding air and the inner sphere l. Both spheres may be made up from hemi-spherical members preferably of stainless steel joined together. Each'of the spheres has a neck portion (la and 2a.) and the space between the two necks is sealed with an annular disc 3. The inner neck la is closed atthe top by a cap member 4 containing a number of passageways. One passageway 5 that extends partially through the cap in an axial direction and then turns hoizontally is provided for filling the sphere l with liquid oxygen. The outer end of this passageway is threaded for receiving a pipe stub 6 to which is connected a T nipple I, and a stub conduit 8 and a manually actuated filling or inlet valve 9 are connected to the nipple I. The inner end of passageway 5 is extended nearly to the bottom of the inner sphere by means of an inserted tube l2. The flask is filled with liquid oxygen by coupling a supply pipe 13 to the inlet side of the valve -9 and opening agas exhaust valve which will be described later. The neck portion la of the inner vessel extends downwardly into the main body portion for a distance sufiicient to prevent overfilling with liquid oxygen, the distance depending upon the amount of working pressure to be used. Liquid oxygen expands rapidly upon being warmed so that its density changes from 72 lbs. per cu. ft. at sea level pressure to approximately 64 lbs. per cu. ft. at lbs. pressure. This expansion of the liquid itself is capable of producing an increased pressure which is not dependent upon the temperature of the liquid and has proven troublesome in the past when the converters were overfllled. By so extending the neck portion la, overfilling is prevented and asmall space is left at the top of the container into which the liquid oxygen cannot be introduced.

Another passageway M in the cap 4 opens into the neck I a and the outer end of this passageway is also threaded for receiving a stub conduit I5 onto which is threaded a four-way nipple l6.

Branching oif from the nipple I6 is a safety valve I! which is pressure responsive and opens in the event that the pressure of the gas rises to a danger point, a conduit l8 leading to a pressure responsive switch that will be explained later in more detail, a manually actuated outlet valve [9, and a manually operated gas release valve-29.

A third passageway Zlthrough the cap'4 is provided for a rod 22 of a liquid level indicating device comprising a float 23 having an arm 24 connected by means of a U clamp 25 to a shaft 26 on which is fixed a pinion gear -21 'that meshes with a gear 28 secured to the lower end of rod 22.

The shaft 26 is journalled at one end ofa bracket 29, the other end of this bracket being fastened to the inner surface of the inner hollow sphere. The upper end of rod 22 enters a liquid level gauge 30 that is shown particularly well in Figs. 8 and :9 supported upon cap 4. The gauge includes a graduated scale 3! swept by a pointer 32 that is rotated by the rod '22 as the latter rot-ates with the rise and fall of float 23 withchanges in the level of the liquid oxygen. f

Surrounding the outer shell 2 and serving as a support for the oxygen converter are a pair of dished cap members 35, 36 having rim portions 31, 38. These rims are provided with .two series of apertures 39, 49 spaced evenly around them. The apertures 33 in the top and bottom cap members 35; 36 are aligned to receive spacing bolts 4! which secure the caps snugly on the outer shell 2. A multiplestrand cable 42 having a. very high tensile strength such as used for the control cables of aircraft is woven back and forth through the other series of apertures 40 in the two cap members in an interlacing manner and .serves as a safety device for protecting personnel from bodily harm in the event of accidental rupture of the inner vessel I. Should the latter break, and liquid oxygen leak out into the otherwise evacuated I space between the inner and outercontainers I and 2, the oxygen w'ould of course be converted into vapor at a. high rate due to the fact that the wall of the outer container 2.is at ambient .temperature as compared with a temperature of-1-83" C for the liquid Oxy en and thus mightresult an explosion of the outer container. .The'in'ter laced metal cap members 35, 3B strengthen the outer container 2 and reduce the possibility of bursting. However should the latter take place, the cap members 35, 36 will serve to prevent the vessel from flying apart as the wire cable-42 is made strong enough to hold the caps togetherregardless of what happens to the oxygen vessel.

The spacer bolts 4| also help in a limited degree .to reduce the explosion effect of the outer. container 2 but these cannot berelied upon to a y great extent because the rims 31, 38 have been found to tear at the bolt holes,

As an extra safeguard againstbursting-of the apparatus, a plurality of small holes, 33 may be drilled through an exposed portion of the Wall of the .outer vessel and these sealed with a soldered cover plate 34 of copper designed toglve way at a pressure of approximately 75 lbs/sq. in.

The bottom cap member '38 is fixed'to a dished support 44 that serves as a floor standfor the oxygen converter.

A bracket 45 made from strap material that is bolted to the upper cap member 35'serves as a support for a warming coil 46 which is connected to the'outlet side of the gas outlet valve 18 andalso supports ,a pressure responsive switch 41 and a relay 48. As'shown' in Fig, '3, the pressure respons'ive switch 4'? "includes a fixed commute and movable contact 59, the latter being actuated by armature 5| linked to a bellows 52 to which the conduit I8 is connected. The latter as previously explained is connected to the four way nipple l6 and hence bellows 52 is actuated in response to the pressure of the gaseous oxygen at the outlet side of-the converter,

A short conduit"j53 extends from the 'T nipple I in the liquid inlet line to a nipple 54 which is placed in the gas outlet line between the outlet valve l9 and the entrance to warming coil 46. A manually adjustable needle valve 55 is placed in conduit '53 and as will later be explained can be used to admit liquid oxygen directly into the warming coil 46 when it is desired to increase the normal rate of flow of gaseous oxygen from the converter. An additional manually controlled valverfit may be connected at the exit of the warming coil 46.

When the converter is initially filled, the liquid oxygen .56 is at an approximate temperature of l83 C.'. and at atmospheric pressure, under which conditions it is substantially in equilibrium. The liquid is converted to vapor form by the application of heat which is derived from an electrical heater unit 5'! of the resistance type which is enclosed within a copper jacket .58. The lower end of the latter is reduced, passed through the wall of the inner vessel 1 and there connected to the lower end of a metal conduit 59 preferably of Monel, a nickel copper alloy. The reduced portion of jacket 58 can be spot welded to the inner vessel at the point where it passes through the vessel wall to anchor itin place. I

Mounted beside the heater unit 51 is a thermostat Bl comprising a pair of bimetallic leave type contacts 62, .63 which are normally closed as shown in Fig. 2 of the drawing. The thermostat is also housed within a metal jacket 54 that is connected by a metal strap to jacket 58 so that the heater unit .51 and thermostat 6| will be in good heat transfer relationship. I The thermostat jacket 64 also has a reduced end passed through and welded to the wall of the inner vessel that connects to a Monel conduit viiii.

The two conduits 59 and 66 extend upwardly in the evacuated space between the inner and outer vessels 1, 2 and on opposite sides thereof, and emerge through openings '67 and E8 providednear the top of the outer vessel 2 and the upper cap 35. The openings .81 in the outer vessel 2 are of course sealed around the conduits 59, 6,6 so that the vacuum between the vessels is not disturbed. Furthermore, it will be evident that'by extending "the Monel conduits 59, 1613 nearly up to the neck to be of the electromagnetic type and includes-a coil 69, an armature 10 carrying contact ll biased away from the coil .core 12 by spring 73 and a stationary contact member '14.

.The various circuit connections linking the electric heater element, the thermostat, the pressure switch and the relay include; a lead l5between a terminal 15 '(to which the positive side of a power supply line is connected) and the movable contact H of relay 48; a conductor TI .connecting the stationary relay contact 14 to one terminal on the oxygen heater resistor 51 through a fuse 78; a lead 19 extending from one side of the relay coil 69 to contact 62 of the thermostat 8|; a conductor 8| connectin the other thermostat contact 63 with the movable contact 50 on the pressure switch 41; and a lead 82 extending between the stationary contact 49 of the pressure switch to the power input terminal 16. The other terminal of the relay coil 69 is grounded as are also the other terminal of the resistor unit 51 and the other terminal 83 of the power supply line. The ground connections may be made through the metal parts of the converter apparatus such as the jacket 58 and the relay housing and these connections are indicated by the usual symbol on the drawing.

Operation The improved oxygen converter operates in the followin manner: Referring now to Fig. 3 the converter is first filled with liquid oxygen through the inlet valve 9. During the filling phase, the gas discharge valve 20 is opened to allow the escape of gas produced by the initial evaporation which is usually quite high at first since the evacuated container isusually warm. After the inner vessel I has been filled to the lower end of the neck la, the valves 9 and 28 are enclosed.

Referring now to the electrical circuit shown in Fig. 3, it will be seen that at this time, contacts 49, 5% of the pressure switch 41 are closed, as are also the'contacts 62, 63 of the thermostat 6|. Hence as soon as power is applied to the terminal 16 on the relay housing, a circuit will be completed through the contacts of the pressure switch and thermostat to energize the relay coil 89 thus closing relay contacts ll, 14 and completing the circuit for energizing the electrical heater element 51. Assuming for the present that valve 55 be closed and gas outlet valve l9 set to a desired opening, the oxygen will begin to vaporize and pass out through valve 19 into the warming coil 16 as soon as it has been sufiiciently heated by the resistance element 51. Warming coil 66 is especially needed where the apparatus is usedto dispense oxygen to a patient in an oxygen tent since its temperature must obviously be raised somewhat if it is to be breathed by the patient without discomfort.

The current will continue to flow through the heater element 51 until the body of liquid oxygen attains a temperature to establish equilibrium for a vapor pressure equal to the pressure at which the pressure switch is set to operate. At this point the bellows 52 will have expanded sufficiently to cause the contacts 49 and 58 to be separated whereupon the coil 69 of relay 48 is deenergized and relay contacts 1|, M are then broken to interrupt the energizing circuit for the heater 51. When the vapor pressure drops, the contacts of the pressure switch and relay are reclosed and the heater element 51 is reenergized. Thus so long as the apparatus is connected to the line, the oxygen will be converted at a controlled rate as determined by the setting of the gas outlet valve l9 and the wattage or heating capacity of resistor 51,

The thermostat 6| functions as a safety device. As long as there is a sufficient amount of liquid oxygen within the vessel I, most of the heat generated by the heater 5'! will be absorbed by the liquid and hence the bimetallic leaf contacts 82, 83 will remain closed. However, when the level of the oxygen falls nearly to the bottom of the inner Vessel I, more of the heat from heater vaporized as before.

5'! will betransferred to thebimetallic leaves 62, 63 by conduction through the copper jackets 58 and and the leaves will-ultimately become sufficiently'heated to break the connection there-between, thus openingthe circuit to the relay coil 69 and shutting off the power to the heater unit 51.

rates, the valve 55 between the liquid inlet and the-warming coil 46 is closed. However with this improved construction. the normal delivery rate of gaseousoxygen may be raised when necessary in either of two different manners. If itis desired to obtain a somewhat prolonged flow of gaseous-oxygen at arate greatly'in excess ofthat in the container above the liquid oxygen as re-' lated to the much lower pressure in the warming coil'46 will-soon force liquid oxygen upwardly through the filling tube lz until it reaches the level of the branch conduit 53. Liquid oxygen now flowspast opened valve 55 and is admitted directly into the warming coil 46 where it is immediately vaporized and at a rapid rate due to the fact that the temperature of coil 46 is practically the same as that of the surrounding air. The rate at which oxygen vapor is delivered from the converter with valve 55 open and valve it closed exceeds by far the delivery rate established when valve 55 is closed and valve [9 opened.

If it is desired to use the converter under conditions where the demand rate for gaseous oxygen is normal and ordinarily substantially constant, but the converter is occasionally called upon to deliver gaseous oxygen at a higher rate to satisfytemporary peak demands, valve 55 can be set to its open position and valve I 9 set slightly open. With the valves in these positions, the

normal demandofoxygen, for example 50 liters/ V warming coil 46 would then establish a pressure difierential suflicient to lift liquid oxygen in the tube 12 to thelevel of conduit 53 and liquid oxygen would then bev admitted directly into warming coil. 46 for direct vaporization, to thus supply the required excessabove normal. When the peak demand drops ofl, the vapor pressure in warming coil 46 again rises and direct admission of liquid oxygen into warming coil to ceases.

In conclusion it will be understood that while we have shown and described a preferred embodiment of our improved oxygen converter, changes in the specific construction and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United states of America for governmental purposes without the payment of any royalties thereon or therefor.

We claim:

1. Apparatus for dispensing liquid oxygen and the like in gaseous form comprising a heat insulated vessel, a valve controlled liquid inlet tube,

In operating'the apparatus at normal delivery said tube extending into the: lower part of: said vessel, means for heating the. liquid to convert it intogas. means for controlling: the operation ofsaid heating means in. accordance. with the;

gas, pressure, a. gas; outlet, an outlet ;valve for controlling the. flow of gas betweenl said, vessel and gas outlet, and a valve controlled conduit interconnecting said inlet; tube with. said. gas tlet on the discharge side. of said outlet; valve.

2; Apparatus for dispensing liquid oxygen and:

t e; like in gaseous form! comprising; a. heat'insu l ted: vessel, a valve control-led; liquid: inlet tube, said. tube extending into theilower part of. said vessel,v means ior heating, the liquid to; convert i ii; intorgas means. for controlling the operation of. saidv heating means irr accordance with'the'. gas; pressure, a warming, coil connected.- toa gas Qutlet from saidvessel, an. outlet valve forxcontrolling, the flow of. gas into said; warming coil; and a valve. controlled conduit. interconnectin said inlet tube with said warming col-la. at the discharge side oi saidoutlet. valve; l

3;. Apparatus for dispensing, liquid oxygen and the like in gaseousiorm comprising; a. heat insu.-- la-ted; vessel, a tubeextending into the lower part of said vessel, means for" heating the liquid. to convert it into a gas. means, for controlling. said heating means. in accordance with the gas; pressure, a, gas. outlet, a valve; for controlling the. flow of gas. trom said vessel; to said outlet; a. con-- duit connectingsaid tube; with said gasoutlet, andvalve. means. in said conduit; whereby. the

liquid may be pulled oft from saidcontainer into around the rims, and a reinforcing cable woven.

back and forth through the. aperturesin said: rims and. interlacing. the. cap members together. 5'. A vessel as defined in claim 4 and further including a plurality of: spacing boltsv interconnecting the rim portions of-saidicapc members.

61. Apparatus for dispensing. liquid? oxygen and the: like in vapor. form comprising a double walled. evacuated: vessel, said vessel being of gen-- erallysphericalv shape and provided with a neck portion,v an electrical heater element and an adjacent thermostatic switch element in the lower part or said vessel, jackets: enclosing said switch and heater elements, and conduits extending" from said jackets: through the inner vessel wall and' upward'ly between: the inner and outer vessel 8;. walls said conduits passing; out through. the outerwal-l adjacent. the vessels: neck.

7;. Apparatus for dispensing liquid oxygen and the. likeinvapor form comprising a double walled evacuated vessel, said vessel being of generally spherical shape and provided with aneck portion, an electrical heater element and an adjacent thermostatic switchelement in the lower part of said vessel, metallic. jackets enclosing said switch and heater elements, said jackets being provided with neck portions extending, through the inner wall of; said vessels and sealedthereto;. and. a. tube extending; from. the neck portion. of- 83-61110): said: jackets; upwardly between the vessel walls, said tubes passing out through the outer wallof said vessel near its neck and sealed thereto.

8. Apparatus for converting, liquid oxygen and the like into gas comprising, a double wall insulating vessel for the liquid; said; vessel being: of generally spherical shape, an electrical heater element in vesseli, a thermostatic: switch in: said vessel adjacent. said: heater element. upper and" lower-cap members; for the outer wall of said: vessel; said cap members being. provided with adjacent. rim portions;. a reinforcing cable interlacing said can members around the: rim portions thereof, a bracket upstanding from the top; cap member, a warming tube connected to a gas outletfrom said vessel, said tube-being. coiled. about said; bracket, gas: pressure responsive switch. means supported by said bracket, a relay supported by said bracket, circuit. means connecting said switches for operation in: series to controlsuid relay, and circuit means: for connecting said heater element through contactson said relay to a source of power,

9. Apparatus for converting'liquid: oxygen and like as: defined in claim 8 whereinthe outer wall of said vessel is provided with a plurality of closely adjacent apertures sealed by a frangible cover plate;

JOHN A. MATHIS'. ROLAND W.

REFERENCES CHiEDz- The following references are of record in the file ofthis. patent :1

UNITED STATES PATENTS.

Number Name Date 139M 44? Heylandt Mar; 14, 1933 2,376-,831 Stearns May 22, 1945' 2401365l- Mathis et a1; Jun-e l, 1946 25423G3l Akerman et a1 JulyB, 1947 2,434,956 Prentiss Jan. 27, 1948 

